1) Field of the Invention
The present invention relates to improving the speed of linear reciprocating movement of a load, the energy efficiency, and durability of a liner actuator apparatus. The load is, for example, an inlet valve, an exhaust valve, or a fuel injection valve of an automobile gasoline engine.
2) Description of the Related Art
A prior art linear actuator apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-199411. This linear actuator apparatus is used as an actuating apparatus that linearly reciprocates to open or close the inlet valve or the exhaust valve of the automobile gasoline engine.
The configuration of this prior art linear actuator apparatus will be explained in detail below. The linear actuator has an actuating unit. The actuating unit includes a magnetic path member comprising a magnetic flux generator equipped with an electromagnetic coil by winding to generate a magnetic flux; and a magnetic field forming section that has at least two pole shoes to form at least one magnetic field region by distributing the magnetic flux. The linear actuator further has a magnetizing member fitted to a mover and having two magnetized surfaces having a different magnetic polarity from each other; an electric current supply unit that supplies a driving current having a magnetism corresponding to either the outward direction or the inward direction of the first mover, to the electromagnetic coil; and a valve stem and a valve element integral with the mover.
The linear actuator apparatus operates as explained below. When the current is not supplied to the electromagnetic coil, the valve element is located at a predetermined position (reference position). When a direct current flowing in a predetermined direction is supplied to the electromagnetic coil, the valve element moves in the predetermined direction and is located at an open position, corresponding to the size of the magnetic flux density. Further, when a direct current flowing in a direction opposite to the predetermined direction is supplied to the electromagnetic coil, the valve element moves in a direction opposite to the predetermined direction and is located at a closed position, corresponding to the size of the magnetic flux density.
The present invention relates to an improvement in the linear actuator apparatus.
The linear actuator apparatus, which linearly reciprocate a load, according to one aspect of the present invention has a first linear actuator including a first mover capable of linearly reciprocating in a first direction and a second direction, the first mover being connected to the load; a second linear actuator including a second mover capable of linearly reciprocating in the first direction and the second direction, the second mover being equipped with an accumulator; and a connecting unit that connects the first mover and the second mover so as to be able to move relative to each other linearly in the first direction and the second direction. The shift of the first mover is larger than that of the second mover. Moreover, the accumulator has a structure such that the accumulator accumulates energy by the shift of the second mover in one of the first direction and the second direction, and shifts the second mover in other one of the first direction and the second direction by discharging the accumulated energy, and the first mover and the second mover have an abutting surface, respectively, which abuts against each other when the accumulator accumulates or discharges energy, to thereby transmit energy to each other via the accumulator.
The linear actuator apparatus, which linearly reciprocate a load, according to an another aspect of the present invention has a first linear actuator including a first mover capable of linearly reciprocating in a first direction and a second direction, the first mover being connected to the load; a second linear actuator including a second mover capable of linearly reciprocating in the first direction and the second direction, the second mover being equipped with an accumulator; and a connecting unit that connects the first mover and the second mover so as to be able to move relative to each other linearly in the first direction and the second direction. The shift of the first mover is larger than that of the second mover. Moreover, the accumulator includes a first accumulator having a structure such that it accumulates energy by the shift of the second mover in the first direction due to the operation of the second linear actuator, and shifts the second mover in the second direction by discharging the energy accumulated by the operation of the second linear actuator; and a second accumulator having a structure such that it accumulates energy by the shift of the second mover in the second direction due to the operation of the second linear actuator, and shifts the second mover in the first direction by discharging the energy accumulated by the operation of the second linear actuator. In addition, the first mover and the second mover respectively include a first abutting surface that abuts against each other when the second mover shifts in the second direction due to the discharge of energy by the first accumulator, to transmit the energy discharged from the first accumulator to the load; and a second abutting surface that abuts against each other when the second mover shifts in the first direction due to the discharge of energy by the second accumulator, to transmit the energy discharged from the second accumulator to the load.
The actuating control method according to still another aspect of the present invention is realized on the linear actuator apparatuses according to the above-mentioned aspects of the present invention and comprises, at the time of startup, actuating the second linear actuator to shift the second mover in one of the first direction and the second direction and actuating the first linear actuator to shift the first mover in the same direction in which the second linear actuator is actuated.
The actuating control method according to still another aspect of the present invention is realized on the linear actuator apparatuses according to the above-mentioned aspects of the present invention and comprises damping the shift of the first mover by the action of the accumulator for accumulating the energy and by controlling the actuation of the second linear actuator.
These and other objects, features and advantages of the present invention are specifically set forth in or will become apparent from the following detailed descriptions of the invention when read in conjunction with the accompanying drawings.